This invention relates to an ink jet recording apparatus wherein a subtank for supplying ink to a recording head is mounted on a carriage on which the recording head is mounted, and the subtank is replenished with ink in succession from a main tank via an ink replenishing tube, a method of replenishing ink to the subtank, and a method of checking the replenished amount of ink to the subtank.
An ink jet recording apparatus can form small dots at a high density with relatively small noise at the print time, and thus nowadays is used for various types of print including color print. Such an ink jet recording apparatus generally comprises an ink jet recording head mounted on a carriage and moving in a width direction of recording paper, and a paper feeder for relatively moving the recording paper in a direction orthogonal to a move direction of the recording head so that ink drops are ejected from the recording head based on print data, to perform recording on the recording paper.
The recording head capable of ejecting black ink, yellow ink, cyan ink, and magenta ink, for example, is mounted on the carriage and not only text print in black ink, but also full color print is enabled by varying a ratio of the respective inks ejected.
On the other hand, in this kind of recording apparatus provided for offices or business, for example, it becomes necessary to dispose a large-capacity ink cartridge to deal with a relatively large amount of print, and thus a recording apparatus of the type wherein a main tank as an ink cartridge is placed in a placement unit (cartridge holder) placed on a side of the recording apparatus main unit, for example, is provided.
Subtanks are placed on the carriage on which the recording head is mounted and each subtank is replenished with ink from the main tank via an ink replenishing tube, and further ink is supplied from each subtank to the recording head.
By the way, nowadays a large-sized recording apparatus with a long scanning distance of a carriage capable of printing on a large paper face is demanded. In such a recording apparatus, to improve throughput, a recording head is provided with a larger number of nozzles more and more. Further, to improve throughput, a recording apparatus wherein while print is executed, each subtank mounted on a carriage can be replenished with ink in succession from a main tank and ink is supplied stably from each subtank to the main tank is demanded.
In such a recording apparatus, an ink replenishing tube needs to be connected from the main tank to each subtank corresponding to each ink and the scan distance of the carriage is large and thus the tube run length grows inevitably. Moreover, a recording head is provided with a larger number of nozzles as mentioned above and thus a technical problem is involved wherein the consumed ink amount is large, the dynamic pressure of ink is thus raised in each ink replenishing tube connected from the main tank to each subtank, and the replenished amount of each subtank with ink is thereby insufficient.
As one means for solving such a problem, for example, a configuration for applying an air pressure to the main ink side and generating a forcible ink flow by the air pressure from the main tank to each subtank for replenishing the subtank with necessary and sufficient ink can be adopted.
To attempt to adopt such a configuration, it is necessary to manage so that the ink amount in each subtank always becomes a predetermined range, and the necessity of adopting a function capable of adjusting the acceptance amount of ink from the main tank in each subtank occurs.
It is therefore an object of the invention to provide an ink jet recording apparatus capable of properly managing the amount of ink with which a subtank is replenished from a main tank, a method of replenishing ink to a subtank in the recording apparatus, and a method of checking the replenished amount of ink to the subtank.
In order to achieve the above object, according to the invention, there is provided an ink jet recording apparatus comprising:
a recording head, mounted on a carriage which reciprocately moves in a widthwise direction of recording paper;
a subtank, mounted on the carriage for supplying ink;
a main tank, storing ink which is replenished to the subtank;
an ink amount detector, which detects an amount of ink stored in the subtank; and
a replenishment controller, which controls replenishment of ink stored in the main tank to the subtank, in accordance with the ink amount detected by the ink amount detector.
According to the invention, there is also provided a method of replenishing ink stored in a main tank to a subtank mounted on a carriage reciprocately moving in a widthwise direction of recording paper, together with a recording head, which are incorporated in an ink jet recording apparatus, the method comprising the steps of:
applying pressure generated by a compressor to the main tank;
operating an ink replenishing valve provided in a replenishment passage which connects the main tank and the subtank, so as to be opened and closed repeatedly in accordance with an amount of ink stored in the subtank.
According to the invention, there is also provided a method of checking replenishment of ink stored in a main tank to a subtank mounted on a carriage reciprocately moving in a widthwise direction of recording paper, together with a recording head, which are incorporated in an ink jet recording apparatus, the method comprising the steps of:
detecting an ink amount replenished to the subtank;
discharging ink from the recording head when it is detected an ink overflow state in which the replenished ink amount detected by the detecting step exceeds a predetermined value;
checking whether the subtank is in the ink overflow state by detecting again an ink amount replenished to the subtank, after the discharging step;
continuing a printable state of the apparatus when the ink overflow state is not detected by the checking step; and
determining an error state of the apparatus when the ink overflow state is detected by the checking step.
Alternatively, the checking method may comprise the steps of:
detecting an ink amount replenished to the subtank;
discharging ink from the recording head when it is detected an ink overflow state in which the replenished ink amount detected by the detecting step exceeds a predetermined value, while incrementing a number of which the ink overflow state is detected;
repeating the discharging step and the incrementing step while comparing the detected number with a predetermined number; and
detecting an error state of the apparatus when the detected number reaches the predetermined number.
Alternatively, the checking method may comprise the steps of:
detecting an ink amount replenished to the subtank;
performing a predetermined amount of printing when it is detected an ink overflow state in which the replenished ink amount detected by the detecting step exceeds a predetermined value;
checking whether the subtank is in the ink overflow state by detecting again an ink amount replenished to the subtank, after the printing step;
continuing a printable state of the apparatus when the ink overflow state is not detected by the checking step; and
determining an error state of the apparatus when the ink overflow state is detected by the checking step.